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 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
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package java.awt.dnd;

import java.util.EventListener;

/**
 * The <code>DragSourceListener</code> defines the
 * event interface for originators of
 * Drag and Drop operations to track the state of the user's gesture, and to
 * provide appropriate &quot;drag over&quot;
 * feedback to the user throughout the
 * Drag and Drop operation.
 * <p>
 * The drop site is <i>associated with the previous <code>dragEnter()</code>
 * invocation</i> if the latest invocation of <code>dragEnter()</code> on this
 * listener:
 * <ul>
 * <li>corresponds to that drop site and
 * <li> is not followed by a <code>dragExit()</code> invocation on this listener.
 * </ul>
 *
 * @since 1.2
 */

public interface DragSourceListener extends EventListener {

  /**
   * Called as the cursor's hotspot enters a platform-dependent drop site.
   * This method is invoked when all the following conditions are true:
   * <UL>
   * <LI>The cursor's hotspot enters the operable part of a platform-
   * dependent drop site.
   * <LI>The drop site is active.
   * <LI>The drop site accepts the drag.
   * </UL>
   *
   * @param dsde the <code>DragSourceDragEvent</code>
   */
  void dragEnter(DragSourceDragEvent dsde);

  /**
   * Called as the cursor's hotspot moves over a platform-dependent drop site.
   * This method is invoked when all the following conditions are true:
   * <UL>
   * <LI>The cursor's hotspot has moved, but still intersects the
   * operable part of the drop site associated with the previous
   * dragEnter() invocation.
   * <LI>The drop site is still active.
   * <LI>The drop site accepts the drag.
   * </UL>
   *
   * @param dsde the <code>DragSourceDragEvent</code>
   */
  void dragOver(DragSourceDragEvent dsde);

  /**
   * Called when the user has modified the drop gesture.
   * This method is invoked when the state of the input
   * device(s) that the user is interacting with changes.
   * Such devices are typically the mouse buttons or keyboard
   * modifiers that the user is interacting with.
   *
   * @param dsde the <code>DragSourceDragEvent</code>
   */
  void dropActionChanged(DragSourceDragEvent dsde);

  /**
   * Called as the cursor's hotspot exits a platform-dependent drop site.
   * This method is invoked when any of the following conditions are true:
   * <UL>
   * <LI>The cursor's hotspot no longer intersects the operable part
   * of the drop site associated with the previous dragEnter() invocation.
   * </UL>
   * OR
   * <UL>
   * <LI>The drop site associated with the previous dragEnter() invocation
   * is no longer active.
   * </UL>
   * OR
   * <UL>
   * <LI> The drop site associated with the previous dragEnter() invocation
   * has rejected the drag.
   * </UL>
   *
   * @param dse the <code>DragSourceEvent</code>
   */
  void dragExit(DragSourceEvent dse);

  /**
   * This method is invoked to signify that the Drag and Drop
   * operation is complete. The getDropSuccess() method of
   * the <code>DragSourceDropEvent</code> can be used to
   * determine the termination state. The getDropAction() method
   * returns the operation that the drop site selected
   * to apply to the Drop operation. Once this method is complete, the
   * current <code>DragSourceContext</code> and
   * associated resources become invalid.
   *
   * @param dsde the <code>DragSourceDropEvent</code>
   */
  void dragDropEnd(DragSourceDropEvent dsde);
}
